Should the burden of proof shift after cops drink?

“rather than call the shooting justified, the judge said that the prosecution failed to prove it was unjustified, as was its burden” (http://www.nytimes.com/2008/04/26/nyregion/26bell.html?hp) and

“In the Bell shooting, undercover officers said that they stayed within the allowed limit of two alcoholic beverages, but they were not tested.” (http://www.nytimes.com/2008/04/26/opinion/26sat1.html?hp).

My question is, should the burden shift to the defense to prove that they were justified when an officer fires his or her weapon while under the influence?